Medical balloons have been used in a number of different applications including dilation of bodily vessels and expansion of medical devices such as stents. In the former application, the medical balloon is delivered on a catheter to a stricture in a vessel and expanded to open the stricture. Expansion of the balloon compresses any plaque present at the stricture. In the latter application, a stent, stent-graft, graft or other prosthesis disposed about a medical balloon may be delivered on a catheter to a desired location in a bodily vessel and expanded by inflating the balloon.
In delivering the medical balloon to the desired bodily location, the catheter must traverse tortuous bodily vessels. Typically, a guidewire will be used to facilitate delivery of the catheter to the desired bodily location. In the case of an over-the-wire (OTW) catheter, for example, the guidewire is positioned within a lumen of an over-the-wire catheter with the distal tip of the guidewire just proximal to the distal tip of the catheter. The catheter and guidewire are advanced through a guiding catheter to the distal end thereof. The guidewire is then advanced out of the distal end of the guiding catheter into the patient""s coronary vasculature until the distal end of the guidewire crosses the desired location in the vessel. The catheter is next advanced out of the guiding catheter until the catheter balloon is properly positioned.
To facilitate delivery of the balloon, it has proven advantageous to apply lubricious coatings to various portions of the medical balloon and other components of the catheter including the various tubes that form the catheter.
Although the use of lubricious coatings has proven beneficial, the presence of such coatings may, in certain cases, result in xe2x80x9cwatermelon seedingxe2x80x9d. Where a highly lubricious balloon and a highly lubricious outer shaft is used, the balloon may slip from the constraints of the lesion as the balloon is inflated. xe2x80x9cWatermelon seedingxe2x80x9d, as the slippage is known, can result in inaccurate vessel dilation or inaccurate placement of the stent or other prosthesis. To avoid this, the balloon must be repositioned, adding to the time required by the procedure.
Where the balloon remains fixed in place, another problem which may be encountered involves sliding of a guidewire relative to the balloon.
There remains a need for inventive catheter designs which are not plagued by the problem of xe2x80x9cwatermelon seedingxe2x80x9d and for inventive catheters which do not experience slippage of the guidewire. More generally, there remains a need for inventive balloon catheters which do not experience undesired motion upon inflation of the balloon.
All US patents and applications all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety.
Without limiting the scope of the invention, a brief summary of the claimed embodiments of the invention is set forth below. Additional details of the summarized embodiments of the invention and/or additional embodiments of the invention may be found in the Detailed Description of the Invention below.
A brief abstract of the technical disclosure in the specification is provided as well for the purposes of complying with 37 C.F.R. 1.72.
The invention is directed in one aspect to a balloon catheter comprising an inner tube with a guidewire therein, a medical balloon and an inflation lumen. The medical balloon is disposed about the inner tube and in fluid communication with the inflation lumen. A collapsible portion of the inner tube is constructed to collapse inward upon delivery of an inflation fluid to the medical balloon and grip the guidewire and to release the guidewire upon removal of the inflation fluid. Desirably, the collapsible portion of the inner tube is a distal portion of the inner tube.
In one embodiment of the invention, the collapsible portion of the inner tube is made of an elastomeric material. Desirably, portions of the inner tube adjacent the elastomeric material are made of a non-elastomeric material. In another embodiment, the collapsible portion is at least 2 mm long.
In another embodiment of the invention, the inner tube is characterized by a plurality of wall thicknesses and the wall thickness of at least a portion of the collapsible portion of the inner tube is smaller than the wall thickness of portions of the inner tube adjacent the collapsible portion. Desirably, the wall thickness of the collapsible portion is 0.002 inches or less. The portions of reduced wall thickness may be in the form of circumferential bands, bands which extend about only a portion of the circumference of the inner tube and/or slots which may desirably be substantially longitudinal.
Also, the inner tubes of the inventive balloon catheters may be provided with a plurality of collapsible portions.
The invention is also directed to a balloon catheter comprising an inner tube with a guidewire therein, a medical balloon and an inflation lumen. The medical balloon is disposed about the inner tube and in fluid communication with the inflation lumen. The inner tube includes a first portion and a second portion adjacent the first portion. The second portion is weaker than the first portion and deforms inward upon delivery of an inflation fluid to the medical balloon. The inner tube may optionally comprise a plurality of weaker portions. Locking occurs for inflation beyond a few atmospheres. Desirably, the second portion recoils upon the removal of inflation fluid from the balloon.
The inventive balloon catheter may be provided with a guidewire in the inner tube when manufactured, at the point of use or at any other suitable time. In use, when an inflation fluid is supplied to the medical balloon, the collapsible portion collapses inward on the guidewire securing the inner tube to the guidewire.
The invention is also directed to a balloon catheter comprising an inner tube with a guidewire therein, a medical balloon disposed about the inner tube and an inflation lumen in fluid communication with the medical balloon. A collapsible portion of the inner tube is constructed to collapse inward upon pressurizing the balloon to grip the guidewire and to release the guidewire upon depressurizing the balloon.
The inventive balloon catheters may optionally be provided with a prosthesis disposed about the medical balloon. Suitable prostheses include stents, stent-grafts and grafts.
The inventive balloon catheters may be provided in a number of different configurations including in a rapid exchange configuration, an over-the-wire configuration and a convertible configuration.
In another aspect, the invention is directed to a method of securing a catheter inner tube to a guidewire disposed in the inner tube comprising the steps of providing an inventive balloon catheter as disclosed herein, delivering an inflation fluid to the medical balloon to cause the collapsible portion of the inner tube to collapse inward against the guidewire and secure the inner tube to the guidewire. Upon removal of the inflation fluid from the medical balloon, the collapsible portion of the inner tube desirably releases the guidewire.
In another aspect, the invention is directed to a method of dilating a vessel comprising the steps of providing an inventive balloon catheter as disclosed herein, inserting the catheter in a body and delivering the medical balloon to a desired location in a bodily vessel and inflating the medical balloon to a pressure sufficient to apply a force to the vessel by supplying an inflation fluid to the medical balloon, the supplying of inflation fluid causing the collapsible portion of the inner tube to collapse inward against the guidewire and secure the inner tube to the guidewire. Upon deflation of the medical balloon, the collapsible portion of the inner tube desirably releases the guidewire.
In yet another aspect, the invention is directed to a method of delivering a prosthesis to a desired location in a bodily vessel comprising the steps of providing an inventive balloon catheter as disclosed herein with a prosthesis disposed about the medical balloon, inserting the catheter in a body and delivering the medical balloon to a desired location in a bodily vessel, and inflating the medical balloon to a pressure sufficient to expand the prosthesis and implant the prosthesis in the vessel by supplying an inflation fluid to the medical balloon, the supplying of inflation fluid causing the collapsible portion of the inner tube to collapse inward against the guidewire and secure the inner tube to the guidewire. Upon removal of the inflation fluid from the medical balloon, the collapsible portion of the inner tube desirably releases the guidewire.
Additional details and/or embodiments of the invention are discussed below.